Seasonal variations of major ionic concentration levels in drifting-snow samples obtained from east Dronning Maud Land, East Antarctica

Abstract

Drifting-snow samples were collected at Mizuho Station (74°42' S, 44°20' E, 2230 m a.s.1.) from February to October 1986 and along traverse routes in east Dronning Maud Land (1800-3000 m a.s.1.), East Antarctica, from October 1986 to January 1987. The typical sampling interval was about once a week but two sets of intensive sampling were made at the end of February and November at between 2 h and 1 d intervalsMeasurements for CI-, NO3,SO42and Na+ were made on the drifting-snow samples by ion chromatography. Oxygen-isotope ratios were .also measured .on the samples. Concentrations levels ofNO3-and SO4-show distinctive seasonal variations: high in summer (4.6 neq g-1 for NO3 and 3.3 neq g1 for SO42) and low in winter during mid-March to mid-November(1.0 neq g1 for NO3 and 0.5 neq g1 for SO42). Results obtained at Mizuho Station show that the transition from the summer high values to winter low values takes about 20 d for NO3 and SO42-.The variations in Cl and Na+ concentration levels are small in both autumn and spring (averages are about 1 neq g-l) with greater variability throughout the rest of the year. The intensive sampling data set shows that there is considerable variability within a day with NO3 and SO42- concentration levels up to about a factor of 4 associated with a 10%0 change in 3180 ratios.